The main things that wear on an HS2, HS4 or HS6 SU are the throttle shaft and the body where it goes through.
Years ago SU used to sell .005"? oversized throttle shafts, you reamed the body out to fit it and Bob was yer auntie's brother.
These days they sell bushes for the body and you use a standard shaft. But you need to drill or bore the body in alignment to take the bushes. If you don't watch what you're doing you can eff the body up.
There is also a bloke in Perth? that advertised here a while ago that he could fit miniature sealed ball bearings to SUs (which is what SU should have done in the first place).
